JP5812396B2 - Composite material, continuous casting part, continuous casting nozzle, and continuous casting method - Google Patents

Description

  The present invention relates to a continuous casting part suitable for producing a cast material of pure magnesium or a magnesium alloy, and more particularly to a composite material suitable for a continuous casting nozzle. The present invention also relates to a continuous casting method using the above-mentioned continuous casting nozzle, and a cast material obtained by using the method.

  Conventionally, a molten metal melted in a melting furnace is supplied to a movable mold made of a roll, a belt, etc. via a hot water reservoir, and the molten metal is cooled and solidified by contacting the movable mold, thereby casting material. Continuous casting for continuously producing is known. The molten metal is supplied to the movable mold through a nozzle. Examples of the casting nozzle include those described in Patent Documents 1 and 2. Patent Document 1 discloses a nozzle in which the tip of the nozzle has a three-layer structure of a good heat conduction layer, a low heat conduction layer, and a high strength elastic layer in order to reduce variations in the temperature of the molten metal in the width direction of the material during casting. Is disclosed. Patent Document 2 discloses a nozzle suitable for use when continuously casting pure magnesium or a magnesium alloy. Since magnesium is an active metal, in order to prevent the reaction between the molten magnesium and the nozzle forming material, when the nozzle body is made of an oxide material, the surface that comes into contact with the molten metal is made of a low oxygen material. A nozzle provided with a layer is described.

JP 2006-015361 A JP 2006-263784 A

  However, when the molten metal is supplied from the nozzle to the movable mold, it always comes into contact with the molten metal at a high temperature, which may cause the component components to be lost to the molten metal, or the oxidation of the molten metal or the penetration of the molten metal. Parts wear out and deteriorate. In some cases, this leads to damage of the parts. Deformation of parts and deterioration of molten metal due to deterioration make the flow of molten metal non-uniform, making it difficult to continue long-term continuous casting.

  In addition, a gap is formed between the nozzle and the movable mold at the supply location. This gap can be formed in an area surrounded by an extension line extending in the axial direction of the nozzle from the inner peripheral edge of the nozzle tip and the movable mold. The molten metal slightly flowing into the gap is cooled by the movable mold and solidifies in the gap, thereby locally disturbing the molten metal flow and causing the surface properties of the cast material to deteriorate. In addition, the molten metal that has become a solidified product is considered to be attached to a movable mold (for example, a roll) and cause a surface defect of the cast material.

  The present invention has been made in view of the above circumstances, and one of its purposes is that the deterioration and consumption of parts and the deterioration of the molten metal hardly occur even during long-time production, and between the nozzle and the movable mold. It is an object of the present invention to provide a composite material suitable for forming a continuous casting part capable of continuously casting a cast material having excellent surface quality, in which molten metal does not easily flow into a gap that can be formed. Another object of the present invention is to provide a continuous casting part, particularly a continuous casting nozzle, using the composite material. Still another object of the present invention is to provide a continuous casting method using a continuous casting nozzle and a cast material obtained by the method.

  The present invention achieves the above object by combining a filler with at least a part of a porous body having high mechanical strength and low reactivity with a molten metal such as pure magnesium or magnesium alloy.

  The composite material of the present invention relates to a composite material constituting at least a part of a continuous casting component used when continuously casting a molten pure magnesium or magnesium alloy. The composite material includes a porous body having pores, and a filler contained in at least a part of the surface portion of the porous body that comes into contact with the molten metal. This filler contains at least one selected from nitride, carbide, and carbon as a main component. These materials are materials that have lower wettability to the molten metal than the porous body (hereinafter referred to as a “water repellent material”). Here, the surface portion refers to a three-dimensional region having a certain depth from the surface of the porous body. In the composite material of the present invention, the filler may naturally be included in the porous body in addition to the surface portion, since it is sufficient that the filler is present at least in the surface portion. Moreover, the main component of a filler is a component which occupies 60 mass% or more among fillers.

  According to the composite material of the present invention, a molten metal such as pure magnesium or a magnesium alloy can be repelled at a location where a filler containing a hot water repellent material is contained. Therefore, by producing a continuous casting part (particularly, a continuous casting nozzle) using this composite material, it is possible to prevent the hot water flow during casting from being disturbed, and as a result, a cast material having excellent surface quality is obtained. be able to. In addition, the presence of the filler makes it easy to suppress damage to the porous body due to the heat of the molten metal, oxidation of the molten metal, and penetration of the molten metal into the porous body. If manufactured, the continuous casting parts are not easily damaged. As a result, it is possible to obtain a casting material having a stable surface quality over a long period of time. Furthermore, by setting it as the structure provided with a porous body and the filler contained in the void | hole, it can be set as the composite material which is hard to produce mechanical damage with high toughness. According to the composite material of the present invention, a nozzle having a complex shape and a thin wall suitable for continuous casting can be produced.

  As one form of the composite material of the present invention, it is preferable that the surface of the portion of the porous body where the filler is present is further provided with a coating layer. In that case, a coating layer is set as the structure which contains at least 1 sort (s) selected from nitride, a carbide | carbonized_material, and carbon as a main component. Here, the main component of a coating layer is a component which occupies 60 mass% or more among coating layers.

  By setting it as the said structure, a molten metal can be repelled more effectively in the part which provided the coating layer. Among nitrides, carbides, and carbons, nitrides in particular are easy to play the molten metal without getting wet or reacting with the molten metal, and are excellent in chemical stability. In addition, since nitride is a low oxygen material that does not substantially contain oxygen, it is less likely to be eroded by reaction with pure magnesium or a molten magnesium alloy. Furthermore, since nitride has high thermal conductivity and low thermal expansion, the expansion and contraction due to thermal conduction from the molten metal is small, and the coating layer is difficult to peel off from the surface of the porous body and is not easily damaged.

  As one form of this invention composite material provided with the said coating layer, the said coating layer can be set as the structure containing an alumina as components other than a main component.

  As an element that determines the wettability of the coating layer to the molten metal, the denseness of the coating layer can also be cited as an important factor. Alumina has the effect of improving the density of the coating layer.

  As one embodiment of the composite material of the present invention, the flexural modulus of the porous body is preferably 90 GPa or less.

  If a nozzle for continuous casting is produced using a composite material having a flexible porous body having a flexural modulus of 90 GPa or less, it is possible to obtain good durability even with a thin shape with little chipping or breakage of the member. The nozzle shape necessary for performing stable continuous casting can be used. As a constituent material of such a porous body, carbon or carbide can be cited. Since carbon has high mechanical strength, it is difficult to be consumed and deteriorated even if it is continuously used, has excellent durability, and can be used continuously over a long period of time. In addition, since carbon is excellent in thermal conductivity, temperature variation can be suppressed at a location in contact with the molten metal. Furthermore, since carbon is hypoxic with a low oxygen content, it is possible to prevent magnesium from binding to oxygen. For example, the porous body may be composed of a SiC fiber or carbon fiber formed by pressing, or a C / C composite (Carbon Carbon Composite: a composite material using carbon fiber as a reinforcing material and carbon as a matrix).

  As one form of the composite material of the present invention, the thermal conductivity in the planar direction of the porous body is preferably 15 W / m · K or more.

  If a continuous casting nozzle is produced using a composite material having a thermal conductivity of 15 W / m · K or more in the planar direction of the porous body, the temperature of the continuous casting nozzle in the planar direction during casting is made uniform. be able to. As a result, the temperature of the molten metal in the plane direction during casting can be made uniform, so that the molten metal is uniformly solidified in the movable mold, and a cast material having excellent surface properties can be obtained. As a constituent material of such a porous body, a material made of carbon or SiC can be cited.

  The continuous casting component of the present invention is a continuous casting component used when continuously casting pure magnesium or a magnesium alloy, and at least a part of the portion that comes into contact with the molten pure magnesium or magnesium alloy is the composite material of the present invention. It is formed by.

  When the composite material of the present invention is used to form a continuous casting part, reaction with magnesium can be suppressed, durability and durability can be improved because it is difficult to be consumed or deteriorated due to oxidation or penetration of the molten metal. Can continue.

  The nozzle for continuous casting of the present invention is a nozzle for continuous casting for supplying a molten magnesium of pure magnesium or magnesium alloy to a movable mold for continuous casting, and is formed of the composite material of the present invention.

  By forming the nozzle for continuous casting using the composite material of the present invention, reaction with magnesium can be suppressed, durability and durability can be improved because it is difficult to be consumed or deteriorated due to oxidation by the molten metal or penetration of the molten metal, and a longer period of continuous casting. Can continue. In addition, it is easy to maintain a uniform hot water flow inside the nozzle serving as a molten metal transport path, and the local hot water flow can be prevented from being disturbed.

  As one form of the continuous casting nozzle of the present invention, at least the tip region from the tip surface on the movable mold side to the outer peripheral surface of the surface of the nozzle for continuous casting has wettability to the molten metal compared to the porous body of the composite material. It is mentioned that a low covering layer is provided. In this case, the coating layer is configured to contain at least one selected from nitride, carbide, and carbon as a main component.

  In particular, by forming the tip region of the continuous casting nozzle with the composite material of the present invention, the molten metal can be prevented from flowing into the gap formed between the nozzle and the movable mold. Therefore, the molten metal flow is not locally disturbed by the gap, and the molten metal can be prevented from solidifying, and a cast material having excellent surface quality can be obtained.

  On the other hand, the continuous casting method of the present invention is characterized in that twin roll casting is performed using the continuous casting nozzle of the present invention and a twin roll type movable mold.

  When continuous casting is performed by the twin roll method, the position of the mold surface (the surface of the mold in contact with the molten metal) can be easily held constant. In addition, since the surface in contact with the molten metal appears continuously as the roll rotates, the release agent is applied and the deposits are removed before the surface used for casting comes into contact with the molten metal again. The equipment for performing such operations as application and removal can be simplified. Needless to say, the continuous casting nozzle of the present invention can also be used for continuous casting other than twin roll casting.

  As one form of the continuous casting method of the present invention, when the thickness of the meniscus portion of the molten metal formed in the gap between the continuous casting nozzle and the twin-roll movable mold is D1, and the distance between the rolls is D2, D1 < It is preferable to perform twin-roll casting with the continuous casting nozzle facing a twin-roll movable mold so that 1.4 × D2.

  It is preferable to keep the continuous casting nozzle as close to the movable mold as possible. When the gap between the continuous casting nozzle and the movable mold becomes large, the molten metal leaks into the gap, and if the molten metal that has become a solidified product due to the leakage adheres to the movable mold, it may cause surface defects in the cast material. Because it becomes. In addition, stable and rapid cooling becomes difficult, and it becomes difficult to obtain good quality. However, when the continuous casting nozzle and the movable mold come into contact with each other, the continuous casting nozzle is cooled, so that the molten metal in the nozzle is also cooled, and the molten metal may solidify before contacting the movable mold. is there. On the other hand, if the continuous casting nozzle is made to face the movable mold so that D1 <1.4 × D2, the above problem can be effectively suppressed. By performing continuous casting satisfying the relationship of D1 and D2 using the nozzle for continuous casting of the present invention, a cast material with better surface quality can be produced.

  The cast material of the present invention is obtained by the above continuous casting method of the present invention.

  The cast material obtained by the continuous casting method of the present invention has a uniform surface shape.

  In the present invention, pure magnesium means that 99.0% by mass or more of the Mg component is contained by mass without intentionally adding other elements, and the magnesium alloy means that the additive element and the balance are Mg. And impurities. Examples of additive elements include Al, Zn, Mn, Si, Cu, Ag, Y, Zr, Ca, Sr, Sn, Li, Ce, Be, Ni, Au, and rare earth elements (excluding Y and Ce). Among the element group, at least one kind of element can be mentioned. Such additive elements are preferably contained in the magnesium alloy in an amount of 7.3% by mass or more. Examples of the magnesium alloy containing the additive element include AZ, AS, AM, and ZK in the ASTM symbol. In particular, a magnesium alloy containing 7.3 to 12% by mass of Al, and a magnesium alloy containing 0.1% by mass in total of at least one of Y, Ce, Ca, and rare earth elements has high strength and excellent corrosion resistance. Therefore, it is preferable. In addition, the continuous casting nozzle of the present invention can also be used for continuous casting of a composite material composed of a magnesium alloy and a carbide, and a composite material composed of a magnesium alloy and an oxide.

  According to the composite material of the present invention, a molten metal such as pure magnesium or a magnesium alloy can be repelled at a place where the filler is contained. Therefore, by producing a continuous casting part (particularly, a continuous casting nozzle) using this composite material, it is possible to prevent the hot water flow during casting from being disturbed, and as a result, a cast material having excellent surface quality is obtained. be able to.

(A) is a schematic block diagram of the apparatus for continuous casting which supplies a molten metal to a movable mold | type, (B) is the schematic of the nozzle for continuous casting of a form different from the nozzle for continuous casting with which the apparatus of (A) is equipped.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment>
≪Composite material≫
The composite material of the present invention constitutes at least a part of a continuous casting part used when continuously casting a molten pure magnesium or magnesium alloy. This composite material includes a porous body having pores, and a filler contained in at least a part of the surface portion of the porous body that contacts the molten metal. Here, the surface portion of the porous body is defined as a region having a depth of 5% from the surface of the porous body. Naturally, the filler may be contained up to a position deeper than the surface portion.

[Porous material]
As a porous body, what was formed by compression-molding silicon carbide fiber or carbon fiber and baking it, for example, can be used. There is no restriction | limiting in the form of carbon fiber in a long fiber, a short fiber, etc. Alternatively, a commercially available product (for example, a porous carbon substrate having an average pore diameter of about 5 μm) can be used. In addition, a porous body made of alumina, alumina fibers, or the like can be used.

  Although there is no restriction | limiting in the magnitude | size of a porous body, It is preferable that the porosity is 30 to 70%. When the porosity is 30% or more, the filler can be sufficiently filled inside the pores, and when it is 70% or less, the mechanical strength can be maintained.

[Filler]
The filler contained inside the pores of the porous body contains a material having a lower wettability to the molten metal (hereinafter referred to as a hot water repellent material) as a main component than the porous body. As the material, nitrides such as AlN, BN and SiN, carbides such as SiC and TaC, or C can be used. BN is particularly preferable. Here, a main component is a component whose content in a filler is 60 mass% or more.

  The filling ratio of the filler with respect to the pores in the surface portion of the porous body is preferably 80% or more. By doing so, it is possible to obtain a composite material that can sufficiently play the molten metal, and it is possible to improve the strength of the composite material.

  The particle size of the water-repellent material is preferably 20 μm or less depending on the size of the pores. Since the surface area of the water repellent material can be increased and the molten metal can be easily repelled as the average particle size is made finer, the average particle size is preferably 5 μm or less. The diameter is preferably 1 μm or more.

  The filler may further include a fixing material such as alumina having an effect of making the filling state of the filler dense as a component other than the hot water repellent material. For example, if the filler contains a sticking agent such as alumina together with the hot water repellent material, the sticking agent functions as an adhesive, and the hot water repellent material can be firmly fixed inside the pores.

  The average particle size of the fixing agent is preferably 1 μm or less. When the average particle size of the fixing agent is 1 μm or less, the water repellent material can be firmly fixed inside the pores. Moreover, it is preferable that content of the adhering material in a filler shall be 0.1-30 mass% with respect to a hot water repellent material. When the content is 0.1% by mass or more, the hot water repellent material can be firmly fixed inside the pores, and when it is 30% by mass or less, the blending ratio with respect to the hot water repellent material can be reduced. The material can play the molten metal sufficiently.

  As a method of incorporating the filler inside the pores of the porous body, for example, the porous body is immersed in a slurry in which a powdered water repellent material (adhesive if necessary) is dispersed in an organic solvent or an aqueous solvent. And a method of impregnating the inside of the pores with a filler. After a while in this state, the filler settles inside the pores, and the filler is filled not only on the surface of the porous body but also inside. Thereafter, the solvent is dried and removed, and heat treatment is performed at a temperature of 600 to 800 ° C. to fix the filler inside the pores, thereby obtaining a desired composite material.

  In addition, a vapor phase method or a chemical vapor infiltration method (CVI) can also be used as a method for causing the filler to be contained inside the pores of the porous body. This CVI method is a method in which a raw material gas is introduced around a porous body arranged in a sealed chamber, and a filler is deposited in a film shape in the pores of the porous body.

[Coating layer]
The composite material of the present invention may further include a coating layer having a lower wettability with respect to the melt than the porous body on the surface of the porous body where the filler is present. By providing the coating layer, the water repellency at the position where the coating layer is provided can be further enhanced.

  For the configuration of the coating layer, basically, the same configuration as that of the filler described above can be used. That is, the coating layer contains one kind selected from nitrides such as AlN, BN, and SiN, carbides such as SiC and TaC, and carbon as the hot-water repellent material, similarly to the filler described above. Further, the coating layer may contain a fixing material such as alumina having an effect of densifying the coating layer in addition to the hot water repellent material.

  The content of the fixing material (alumina) in the coating layer is 2 to 10% by mass with respect to the hot water repellent material as the main component of the coating layer (that is, when the hot water repellent material is 100% by mass%, the alumina is Is preferably 2 to 10).

  The coating layer can be formed by fixing a powder as a raw material of the coating layer to the surface of the porous body by heat treatment. For example, when forming a coating layer containing BN as a main component and alumina as a component other than the main component, first, a slurry containing BN powder and alumina powder is prepared. Next, the slurry is applied to the surface of the porous body, and heat treatment is performed. The average particle size of BN powder is preferably 5 μm or less, and the average particle size of alumina powder is preferably 1 μm or less. By doing so, the surface of the coating layer 3 can be made smooth.

  The thickness of the coating layer is preferably 200 μm or more. If the thickness of the coating layer is too thin, there is a risk of peeling from the surface of the porous body due to contact with the molten metal. More preferably, it is 300 μm or more. However, if the coating layer is too thick, the adhesion between the coating layer and the porous body is reduced, and the coating layer may be peeled off from the porous body. Therefore, the thickness of the coating layer may be 1000 μm or less. Preferably, it is 500 μm or less. When the coating layer is made of pure BN, if the coating layer is too thick, the coating layer may become brittle and crack.

≪Continuous casting equipment≫
Next, an example in which the above-described composite material of the present invention is applied to a continuous casting apparatus will be described. FIG. 1A is a schematic configuration diagram of a continuous casting apparatus that supplies molten magnesium 10 or molten magnesium alloy 10 to the movable mold 20. This apparatus includes a melting furnace (not shown) that melts pure magnesium, a magnesium alloy, and the like to form a molten metal 10, a hot water reservoir 30 that temporarily stores the molten metal 10 from the melting furnace, and a molten metal from the melting furnace 30 And a nozzle 1 for supplying the molten metal 10 from the reservoir 30 to the movable mold 20. Then, a pair of rolls 21 (movable mold 20) for forming the cast material 100 by casting the molten metal 10 is provided.

  The nozzle 1 has a cylindrical shape, and an inner peripheral side thereof serves as a transport path for the molten metal 10. In the nozzle 1, one end side having an opening is used as a pouring port 4 for supplying the molten metal 10 to the movable mold 20. The pouring port 4 has a rectangular shape corresponding to the cross section of the casting material 100 such that the major diameter of the pouring port 4 (the width of the casting material 100) >> the short diameter of the pouring port 4 (the thickness of the casting material 100). . The major axis and minor axis of the pouring gate 4 are appropriately changed according to the desired width and thickness of the cast material 100. In addition, for example, the width of the cast material 100 can be changed by arranging weirs on both sides of the pouring gate 4. The other end of the nozzle 1 is fixed to the hot water reservoir 30. A transfer tub 31 is connected to the basin 30, and the molten metal 10 from the melting furnace is supplied to the basin 30 via the transfer basin 31. The molten metal 10 is transported from the sump 30 to the nozzle 1 and supplied from the nozzle 1 to the roll 21. Each of the rolls 21 is a cylindrical body, is opposed to each other with a predetermined interval, and rotates in opposite directions as indicated by arrows in FIG. The interval between the rolls 21 is appropriately selected according to the desired thickness of the cast material 100, but is preferably the same as or slightly narrower than the short diameter of the pouring port 4 of the nozzle 1. A water channel 22 is provided inside the roll 21 so that water is circulated as needed, and the surface of the roll 21 is cooled by this water. That is, the roll 21 has a water cooling structure.

  Casting material 100 can be obtained by casting using nozzle 1 and roll 21. As the molten metal 10 is transported through the nozzle 1, the temperature begins to gradually decrease, and is supplied between the rolls 21 from the pouring port 4 at the tip of the nozzle 1. The supplied molten metal 10 is rapidly cooled and solidified by coming into contact with the rotating roll 21, and is discharged as a cast material 100 from between the rolls 21. Thus, the continuous casting material 100 is obtained by continuously supplying the molten metal 10 between the rolls 21. In this example, a plate-shaped cast material 100 is manufactured.

  A feature of the present invention is that the parts of the continuous casting apparatus are formed of the composite material. Examples of the parts of the continuous casting apparatus include the nozzle 1, the sump 30, the transfer rod 31, and the weir (not shown). At least a portion of the portion of the continuous casting part that contacts the molten metal 10 is formed of the composite material. Furthermore, if all the portions that come into contact with the molten metal 10 are formed of the composite material, it is possible to further suppress wear and deterioration of the continuous casting component. Further, the entire continuous casting part may be formed of the composite material of the present invention. For example, the entire nozzle 1 is composed of the porous body 2, and the porous material 2 is made to contain a filler in the surface portion thereof, thereby causing damage to the porous body 2 (nozzle 1) due to the heat of the molten metal 10, The penetration of the molten metal 10 into the body can be suppressed, and as a result, the surface quality of the cast material 100 can be improved.

  When the thickness (maximum thickness) of the meniscus portion formed in the gap between the nozzle 1 and the roll 21 is D1 and the distance D2 between the rolls 21, the nozzle 1 satisfies D1 <1.4 × D2. In addition, the nozzle 1 may be made to face the roll 21. By doing so, the distance d between the nozzle 1 and the roll 21 can be set to an appropriate value regardless of the sizes of the nozzle 1 and the roll 21. These D1 and D2 can be confirmed by once interrupting the casting.

  As another form of the nozzle 1, as shown in FIG. 1B, a coating layer 3 may be formed on the tip region 1 r of the nozzle 1 (the portion indicated by cross-hatching). By doing so, the molten metal 10 can hardly flow into the gap formed between the nozzle 1 and the movable mold 20. As a result, it is possible to obtain a casting material 100 having excellent surface quality. Here, the front end region 1r of the nozzle 1 refers to the front end surface between the inner peripheral edge and the outer peripheral edge of the nozzle 1 and the outer peripheral surface of the nozzle 1 continuously from the front end surface on the movable mold 20 side of the nozzle 1. It is an area. As the coating layer 3, the same material as described in the item of the composite material can be used.

≪Effect≫
By forming the continuous casting part from the composite material of the present invention, it is difficult for the molten metal 10 to be consumed or deteriorated due to oxidation or penetration of the molten metal 10, and the durability of the part can be increased. A nozzle shape suitable for good casting such as a complex shape can be obtained. Therefore, the continuation of continuous casting can be improved in the long term.

  In particular, since the continuous casting nozzle 1 is formed of the composite material, it is easy to maintain a uniform hot water flow inside the nozzle 1 serving as a transport path for the molten metal 10, and locally prevent the hot water flow from being disturbed. Furthermore, as shown in FIG. 1B, by providing the coating layer 3 in the tip region 1 r of the nozzle 1, the molten metal 10 can hardly flow into the gap formed between the nozzle 1 and the movable mold 20. Therefore, the molten metal flow is not locally disturbed by the gap, so that the molten metal 10 can be prevented from solidifying, and the cast material 100 having excellent surface quality can be obtained.

<Test Example 1>
In this test example, the influence of the filler on the cast material made of the magnesium alloy was examined.

[Sample 1]
First, a porous body 2 in which silicon carbide fibers were compression molded and baked and formed into the shape of the nozzle 1 was prepared. The tip thickness of the porous body 2 was 1 mm, and the width was 300 mm. Further, the porosity of the porous body was 45%, the flexural modulus of the porous body 2 was 90 GPa, and the thermal conductivity in the plane direction of the porous body 2 was 17 W / m · K.

  Next, the inside of the pores in the surface portion of the porous body 2 was filled with aluminum nitride having an average particle diameter of 1 μm. The filling ratio of aluminum nitride to the pores of the porous body 2 was 90%. When filling the inside of the pores with aluminum nitride, first, a slurry containing aluminum nitride having an average particle diameter of 1 μm and alumina powder having an average particle diameter of 0.8 μm was prepared (by mass%, the aluminum nitride powder was When 100, alumina powder is 5). Next, the porous body was immersed in this slurry, and aluminum nitride was impregnated into the pores in the surface portion of the porous body. Then, the solvent was removed by drying, and heat treatment was performed at a temperature of 800 ° C. to fix aluminum nitride inside the pores of the porous body 2.

  A magnesium alloy melt 10 corresponding to AZ91 was supplied from the nozzle 1 to the movable mold 20 to produce a plate-like cast material 100 having a thickness of 5 mm and a width of 300 mm. At this time, the thickness D1 of the meniscus portion was 1.2 times the distance D2 between the rolls 21. In producing the cast material 100, a non-defective rate is obtained when the magnesium alloy melt 10 of 0.5 t / lot is used. The non-defective product rate means that the surface property of the manufactured cast material 100 is visually confirmed, and the surface property deteriorates from the beginning of casting of the cast material 100 with respect to the length of the cast material when the entire molten metal is cast (cracking). Etc.) is calculated. The yield rate and the configuration of the nozzle 1 are shown in Table 1.

  Further, after the continuous casting, when the contact portion that was in contact with the molten metal 10 of each continuous casting component (nozzle 1, sump 30, transfer rod 31) was visually checked, no impregnation of the molten metal was observed and it was noticeable. No deterioration was observed.

[Sample 2]
Sample 2 is different from Sample 1 in that the hot-water repellent material is BN powder having an average particle size of 0.6 μm, and the porous body 2 is formed by compression-molding carbon fiber and baking it into a nozzle shape. Except for these points, it is the same as Sample 1.

[Sample 3]
The sample 3 is different from the sample 2 in that the filler is formed only of SiC and that the filler is impregnated over the entire surface portion of the nozzle 1 (porous body 2) by a chemical vapor impregnation method. Except for these points, it is the same as Sample 2.

[Sample 4]
The sample 4 is different from the sample 2 in that the filler is formed only of C, and the filler is impregnated over the entire surface of the nozzle 1 (porous body 2) by the chemical vapor impregnation method. Except for these points, it is the same as Sample 2.

[Sample 5]
The sample 5 is different from the sample 2 in that an alumina porous body is used as the porous body 2. The bending elastic modulus of the alumina porous body was 180 GPa, and the thermal conductivity in the plane direction was 5 W / m · K. The nozzle of this material was inferior in strength and deteriorated (chips) at the tip of the nozzle during casting. Also, it was difficult to set D <1.4 × D2.

[Sample 6]
The nozzle 1 is different from the sample 1 in that the entire nozzle 1 is made of only SiC fiber material. In addition, the dimensions of the nozzle 1, the cast parts, the casting method, and the method for calculating the yield rate are the same as those of the sample 1. After continuous casting, when the contact portion that was in contact with the molten metal 10 of each continuous casting part (nozzle 1, sump 30, transfer rod 31) was visually checked, the molten metal was impregnated and deteriorated. It has been found.

[result]
Table 1 shows the schematic configuration and the yield rate of Samples 1 to 6 described above. The “filling ratio” in the table is the ratio at which the pores in the surface portion of the porous body 2 are filled with the filler, and in this test example, it was measured by observing the cross section with an optical microscope.

  By comparing the samples 1 to 5 in which the porous material 2 contains the filler and the samples 6 that are not, it can be seen that the non-defective product rate can be improved by making the porous material 2 contain the filler. This is because the wettability of the filler with respect to the molten metal 10 is low, so that the molten metal 10 is repelled by the filler and the molten metal 10 does not easily flow into the interior of the nozzle 1 or between the nozzle 1 and the movable mold 20. It is thought that it is because it is. That is, there is no deterioration or deformation of the member, and the molten metal 10 supplied from the nozzle 1 to the movable mold 20 can flow smoothly. Therefore, in the gap formed between the nozzle 1 and the movable mold 20, the molten metal flow is not locally disturbed, the molten metal 10 can be prevented from solidifying, and the casting 100 having excellent surface quality for a long time is obtained. be able to.

  In addition, by comparing the samples 1 to 4 and the sample 5, the samples 1 to 4 having the bending elastic modulus of the porous body 2 of 90 GPa or less and the thermal conductivity of 15 W / m · K or more are the samples. It was found that the yield rate was higher than 5. It has high toughness, high thermal conductivity, low oxygen, and excellent mechanical strength, so it is not easily consumed or deteriorated even after continuous use, has excellent durability, and can be used continuously for a long time. It is considered that the molten metal 10 supplied to the movable mold 20 can smoothly flow.

<Test Example 2>
In Test Example 2, as shown in FIG. 1B, when the coating layer 3 was further formed in the tip region 1r of the nozzle 1, the influence of the coating layer 3 on the cast material was examined.

  First, the nozzle 1 used for preparation of the sample 4 of Test Example 1 was prepared. On the other hand, a slurry containing 5% by mass of alumina powder having an average particle size of 0.8 μm in the boron nitride powder was prepared. Next, this slurry was applied to the tip region 1 r of the porous body 2 by spraying. Then, heat treatment was performed at a temperature of 800 ° C., and boron nitride was fixed to the surface of the tip region of the porous body 2 to complete the coating layer 3. The surface roughness Ra (arithmetic mean roughness) of the coating layer 3 was 5 μm, the thickness of the coating layer 3 was 200 μm, and the relative density of boron nitride was 95%. The measuring method of the surface roughness Ra was measured according to the method prescribed in JIS B 0601. Specifically, it is an average value of values measured at 5 points at a measurement length of 3 mm.

  When continuous casting was performed using the nozzle 1 provided with the coating layer 3 described above, the yield rate of the cast material was 99% or more. Therefore, if the filler is impregnated over the entire surface of the porous body 2 and the coating layer 3 is formed on the surface of the tip region 1r, the solidification of the molten metal 10 between the nozzle 1 and the roll 21 is effectively suppressed. It was found that it was possible to obtain a cast material having superior surface quality more stably. That is, it has been clarified that the tip region 1r from the tip surface to the outer peripheral surface of the nozzle 1 greatly affects the surface quality of the cast material.

<Test Example 3>
In this test example, it was examined whether the composite material of the present invention is effective for continuous casting parts other than the nozzle 1.

  The condensate 30 and the transfer trough 31 which are parts for continuous casting are also formed in the same shape as the sump and the transport trough of the sample 1 using a porous body (C / C composite) obtained by compression-molding carbon fiber and baking it. Formed. And the filler which mixed the boron nitride and the alumina was filled inside the hole of carbon fiber in the location which each contacts with a molten metal. The formation material of the sump 30 and the transfer rod 31 is different from that of the sample 1, and the formation material and dimensions of the nozzle 1, the dimensions of the sump 30 and the transfer rod 31, and the casting method are the same as those of the sample 1.

  After performing continuous casting using the above-described sump 30 and transfer trough 31, the contact portion that has been in contact with the molten metal 10 of each continuous casting component (nozzle 1, sump 30, and transport trough 31) is visually observed. Examined. As a result, each contact location that was in contact with the molten metal 10 was not impregnated with the molten metal, and no noticeable deterioration was observed.

  The above-described embodiments can be appropriately changed without departing from the gist of the present invention, and the scope of the present invention is not limited to the above-described configuration.

  The composite material of the present invention can be suitably used as a material for forming a continuous casting part that performs continuous casting of pure magnesium or a magnesium alloy. Further, the continuous casting part formed by the composite material, particularly the continuous casting nozzle, is optimal for continuous casting of a cast material having excellent surface properties for a long period of time.

DESCRIPTION OF SYMBOLS 1 Nozzle (nozzle for continuous casting) 1r Tip area | region 2 Porous body 3 Coating layer 4 Pouring port 10 Molten metal 100 Cast material 20 Movable mold 21 Roll 22 Water channel 30 Hot water reservoir 31

Claims (9)

A composite material constituting at least a part of a continuous casting component used when continuously casting a pure magnesium or magnesium alloy melt,
A porous body having pores;
Of the surface portion of the porous body, comprising a filler that is inherent in at least a part of the portion that contacts the molten metal,
The porous body has a thermal conductivity in the plane direction of 15 W / m · K or more,
The filler is a composite material containing as a main component at least one selected from nitride, carbide, and carbon. Furthermore, a coating layer is provided on the surface of the part in which the filler in the porous body is contained,
The composite material according to claim 1, wherein the coating layer contains at least one selected from a nitride, a carbide, and carbon as a main component.   The composite material according to claim 2, wherein the coating layer contains alumina as a component other than the main component.   The composite material according to any one of claims 1 to 3, wherein the porous body has a flexural modulus of 90 GPa or less. A continuous casting part used when continuously casting pure magnesium or a magnesium alloy,
5. A continuous casting part in which at least a part of a portion in contact with a pure magnesium or magnesium alloy melt is formed of the composite material according to claim 1. A continuous casting nozzle for supplying a pure magnesium or magnesium alloy melt to a movable mold for continuous casting,
The nozzle for continuous casting currently formed with the composite material of any one of Claims 1-4. Of the surface of the nozzle for continuous casting, at least in the tip region extending from the tip surface on the movable mold side to the outer peripheral surface, a coating layer having low wettability with respect to the molten metal compared to the porous body of the composite material,
The continuous coating nozzle according to claim 6, wherein the coating layer contains at least one selected from nitride, carbide, and carbon as a main component.   The continuous casting method which performs twin roll casting using the nozzle for continuous casting of Claim 6 or Claim 7, and a twin roll type movable mold. When the thickness of the meniscus portion of the molten metal formed in the gap between the continuous casting nozzle and the twin-roll movable mold is D1, and the distance between the rolls is D2,
The continuous casting method according to claim 8, wherein twin roll casting is performed with the continuous casting nozzle facing a twin roll movable mold so that D 1 <1.4 × D 2.

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